Dredger



SePt- 15, 1942- A. c. CRAWFORD 2,295,717

DREDGER Filed March 14, 1939 '7 SheetsfSheet 1 Sep. 15, 1942.

A. C. CRAWFORD DREDGER Filed March 14, 1939 '7 Sheets-Sheet 2 ATTORNEYS Sept. l5, 1942. A. c. CRAWFORD DREDGER Filed March 14, 1939 7 Sheets-Sheet 3 r ATTORNEYS Sept. l5, 1942.

A; c. CRAWFORD DREDGER '7 Sheets-Sheet 4 Filed March 14, 1939 INVENTOR (im w'afa,

Sept. 15, 1942. A. c; CRAWFORD DREDGER Filed March 14, 1939 7 Sheets-Sheet 5 lNvEN-roR a.. a s A# am u y Sept. l5, 1942. A. c. CRAWFQRDv DRE'DGER Filed March 14, 1959 7 Sheets-Sheet 6 7'0 Anci/MA 6E 75 A/a/MAQS AKI/la@ C (56m wfafa m97" @4079914 ATTORNEYS Sept. 15, 1942.

A. C. CRAWFORD DREDGER Filed March 14, 1939 7 Sheets-Sheet 7 BY .Y i s( ATTORNEYS atented Sept. 15, 1942 UNITED STATES PATENT QFFICE 2,295,717 DREDGER Arthur C. Crawford, Rodeo, Calif. Application March 14, 1939, serial No. 261,785

21 Claims.

The present invention relates to improvements in dredgers, and has particular reference to dredgers used in gold mining operations, although, of course, it may be used for different purposes.

The principal object of the invention is to provide a dredger that is simple in construction, economic in operation and possesses desirable properties of maneuverability.

A further object of my invention is to provide a dredger in which a number of dredging means for facilitating radial travel of the shovel with respect to the axis of its swinging motion.

A still further object of the invention is to improve the maneuverability of the dredger by providing means for holding the dredger against opposing currents, means for advancing the' dredger, means for laterally shifting the same and means whereby all of these means exert a lifting effect on the front section of the dredger to allow the same to clear obstacles.

A further object of the invention is to place all of the means for maneuvering the dredger at a high elevation whereby danger of damage due to obstacles is minimized.

And finally, it is proposed to provide means in connection with a dredger of the character described for facilitating inspection and sampling of the soils and subsoils to be worked on.

Further objects and advantages of my invention will appear as the specification proceeds.

The preferred form of the invention is illustrated in the accompanying drawings, in which:

Figure l shows a side elevation of my dredger with the shovel in position between scooping and ascending operations;

Figure 2, a sideY elevation of the dredger showing the shovel in position prior to the lowering of the same for scooping operation;

Figure 3, a side elevation of the dredger showing the shovel at the beginning of the scooping operation;

Figure 4, a detail view showing the shovel of Figure 3 in a different adjustment;

Figure 5, a side elevation of the dredger showing the shovel in elevated position ready for discharge;

Figure 6, an enlarged detail View of the shovel and operating mechanism, in side elevation;

Figure 7, a section taken along line 1-1 of Figure `6;

Figure 8, a section taken along line 8 8 of Figure 6;

Figure 9, a plan View of the barge on which the dredging apparatus is supported;

Figure l0, a sectional view taken along line Ill- I0 of Figure 6;

Figure 1l a sectional detail view taken along line Il-II of Figure 6;

Figure 12, a schematic view showing in side elevation, a plurality of shovels arranged in cooperative relation alongside of one another.

Figure 13, a schematic plan View of the arrangement shown inA Figure l2, and

Figure 14, a side elevation of a caisson used for inspection and sampling, a portion being shown in vertical section.

While I have shown only the preferred form of my invention, I wish to have it understood that various changes or modifications may be made within the scope of the claims attached hereto without departing from the spirit of the invention.

Referring to the drawings in detail, my dredging apparatus is mounted on a barge I, which may be rectangular in form and prefereably consists of a plurality of sections 2,-3 and 4 securely fastened together by any suitable means. A long recess 5 extends centrally into the barge from in front and forms the Well in which the dredging apparatus operates.

The barge is made to float on a body of water, such as the river indicated at 6, in an upstream direction. For holding and maneuvering the barge I provide the following apparatus:

A cable 'l is stretched across the river or other body of water at a considerable height and secured to any suitable means not shown in the drawings. The barge has a rear gantry 8 and a front gantry 9 rising therefrom, the rear gantry comprising two spaced and hollow supporting posts I0 and a cross-member Il, while the front gantry comprises the two posts l2 and a crossmember I3.

The front gantry has a pulley Ul secured thereto by any suitable means, such as the member I5, and the rear gantry has another pulley I6 secured thereto, the latter being arranged at a higher elevation than the former, it being understood that cable 'I is also higher than pulley I4. Both pulleys are arranged over the median line of the barge, although the front pulley is shown slightly oli-set in Figure 9 to allow a second pulley underneath the former to be shown.

.A cable I'I is secured to the. cross-cable 'I by means of a pulley I8 and is guided underneath pulley I4 and over pulley I6 and downward to a suitable winch not shown. This cable holds the barge against the stream and is used for advance ing the same. It will be noted that the cable has a lifting eiiect on the front sectionqof the barge and may be used to raise the latter whenobstacles are encountered in the-river bed. A- stern line I9 is secured to the winch I9 and leads over a, pulley secured to the gantry at a high elevation tofasultable anchoring` means so as to clear the body of water and possibleobstacles andthis .line servesasfa counter brace to the pull of the head line or cable I'I.v Y Y .Y

lin-dredging operation; it isE customaryVV to start at one -side'of the-river and to stepwise advance slidewise across the river until the other side is reached, whereupon the barge is moved forward to repeattlleoperation in the opposite direction.

For laterally ymoving the barge, I provide the two cables 20, the front ends of which are suitably'anchoredl near the anchoring points for the cross-cable 1 while intermediate portionsV are guided over pulleys-2l suitablyfconnected to the front gantrya-t the elevatinof'thepulleys- I 4 and over pulleys 2'2- associated with the-rear gantryat a higher elevation. The rear ends ofY thesefcables are -secured to suitable-1Winches37;

The barge suppQrts on its'rear section,v and at asuitableelevation, a conventional rotary screen 24, slightly-inclined, and suitably Vactuatedby'pinions 25. The rearen'd of the screen discharges upon a conventional stackerco'nveyor 26, and at the front endI provideasluice'channel- 2 which discharges the dredged material intothescreen.

At the front end of thesluicechannel is pivotally mounted the shovelling apparatus comprising theV shovel- 30,` the*sliovelchannel` 3I and the channel guide 32.. The channel guide is. in the form of an elongated rectangular box having a ilat bottom 33'; verticalsides-34and'inwardly extending flanges 35V projecting from the, upper edges of thesides The upper. bottomedge of this box is swingably: supportedA on' a stationary shaft 36V arranged at the frontend of'the sluice Ychannel 27.

The shovel channel3lf is'presjentedin the; form Y of a long trough, roundedattlie corners asiat 37,

and providedV with laterally' projecting flanges 38 which register with the ii'anges 35 of the guide when the channel isinsidethe latter. rI'he channel is sufficiently` smaller than' theguide to leave space betweenthe flangesand ,between the bottom members for the antiefriction' means shown in Figures 7 and 8.1 Y

The' latterV means are Varranged. so that the channel is always'y supported by anti-friction, means. evenA if'the topi ofthe channel nears the bottom end ofthe guide.V To. accomplish this, I provide, near'the. bottom end of the guide, the roller 39. supported in bearingsllll'rising from the bottom, ofY the. channel; which latter" may'be provided with a suitable reinforcing strip 4I riding onthe. roller between the bearings. lI also `provide, atV the samev end of' guide; rollersA 42 which are supported in bearings secured to the fianges 35 and contact the flanges 38 of the channel.

At the upper end of the guide I provide diferently located anti-friction means, namely two rollers 43 supported on the guide and contacting the corner sections of the channel, and a second set of rollers 44 having bearing in the sides of the guide and riding on the flanges of the channel.

When the upper end of ther channel descends below thetop': end of the guide, the upper rollers of the guide lose contact and I, therefore, substitute rollers 45 and 46 at the upper end of the channel which, upon entering the guide, become active on the bottom and the anges as shown in the drawings.. It will be noted that roller 45 will freely pass between rollers 43 and that rollers 46 will'freely pas's-r inside of rollers 44. The bottom of. the guide is preferably provided with a reinforcing strip 41 for roller 45 to ride on.

It williv thus bef seen that anti-friction means are providedfdr allpofssiblepositions,of the channel intlie-guideg thedovvnward travel of the channel in thgud' being limited" s0 as to prevent the channel from leaving the guide by registering stopslll'and 43)"i The shovel 3D; may b'e of any suitable constructionpis' hinged toi the bottom edge of the shovel channel; as at` 5U, and may be held thereto in eitherfi'xed-l relation or with a certain amount of aifigular play''bystraps 5I. The latter areslott'ed (seeligure 6) and one end of each strapissecure'dfto-an upper portion of the bottom end of the channel byY means of a kpin- 52 which latter maypass through an independent hole-in the strap, or' through the slot itself, because in the- Iattercase, the weight ofthe shovel holds the pinfirmlyi inthe upper end of the slot during the scoopingand ascending operation.

The bodyf'port-ionfoi each, strap is secured to thev shovel by" means of a second pin 53, which may -be'passedi through aregistering hole of the strap a'sjshown in Figure kfi to hold the shovel in xedfposition, or maybe passed through the slot for' allowing the shovel to Vswingfurther back.

y The two relative', positions vwhich may thus be obtained arejindicated in Figures 3` and 4, both of which'showtheshovelatthebeginning of the scoopingV operation. Thegposition of Figure 3 is used forA normal scooping operations thrcugh yielding soil'.f'urination` ,whereas the position of Figure 4' is'intended'L for scraping over hard hed rook;

The shovel movementhis', particularly illus trated in, lliguresjV 1'5j;` Figure 1 showing the shovel in initialposition'v at the Vfront of the barge andlsubstantially o nf thewateri level. From this position it is retractedinto the position of Figure 2, then .droppedintothe position of Figure 3, then pulledv forwardjt'o again reach the position of Figure l', whereupon it is'rmade to ascend to the dumping position ofFigure5v and again lowered tothe positionolf Figure 1. l

The shovel tis operated bymeans of Atwo cables 5 5"and56,- thejiormer'b'eing attached to a crossmeinber'l` A(seejligure'l')` stretching across the topjoi the-s hoveliand` tllieilatterl being Ysecured to the 'baclrofv the* shovel asat 5.8. The cable 56 leads directly to a winchf59, and the cable 55 leads over a pulley 60 supported by a yoke or bail 6I- and pulley-.62j supported; in the upper portion of-the irorit'gantry; toa winch 63;

The bail 6A] istpivotajlly'supported` at 36 in coaxial relation to thev channel guide 32' so that The bail only partakes of the ascending and descending movements of the shovel and remains in the position shown in Figure 1 during the scraping or scooping operation. Suitable means are provided, therefore, to hook the shovel to the bail and to release the latter for ascent, as the shovel passes through the station of Figure 1 in an upward direction, and to reverse the connections on the downward travel, the bail being anchored to the barge and the shovel disconnected from the bail.

The means for effecting the desired changes on each passing of the shovel are particularly illustrated in Figures 6, 10 and 11. Figure 10 shows the means for connecting the bail to the barge. The shovel operates in the long front recess of the barge and the inner walls of the latter defining the recess are provided with inwardly projecting ledges 10 which stop the downward progress of the bail below the water level. In the ledges are pivoted hooks adapted to hook over the sides of the bail and the hooks are driven into firm engagement with the bail by ridges 12 forcing the lower ends of the hooks outwardly. On the return movement of the bucket the hooks are disengaged from the bail by means of pins 13 secured to the shovel striking similar pins 14 projecting from the lower ends of the hooks.

Figure 11 shows the means for connecting and disconnecting the shovel and the bail. The for mer is provided with detents 15 in the sides thereof and the bail carries pivoted bell-crank levers 16 adapted for hooking underneath the detents. On the upward movement the inclined face of the detent pushes aside the levers 16, which immediately upon passing engages with the detent on account of the weight of the horizontal arm 80 of the bell crank lever. This position of engagement is retained in spite of the horizontal arm of the lever passing a pawl 11 pressed against the arm by a spring 18, because the tapered upper face of the arm 80 crowds the pawl away. On the reverse movement of the shovel and the bail, however, the arm 80 strikes the top of the pawl 11 and is thereby made to release the shovel.

It should be observed that the respective engagements and disengagements must be properly timed so that, on the downward travel of the shovel, the bail is locked to the barge before the shovel is disconnected, while on the travel in the reverse direction, the shovel is hooked to the bail before the latter is released from the barge.

The shovel operation of my dredger will be well understood from the foregoing description.

Commencing with the position shown in Figure 1, we will assume that the bail, which, taken by itself, is lighter than the counterweight, is

hooked to the barge by hooks 1I and the shovel 70 is pulled forward by cable which passes over the pulley disposed on the bail. As the shovel advances engagement takes place between hook 16 and the detent 15 for securing the shovel to the bail, and immediately thereafter pin 13 crowds pin 14 inwardly for releasing the bail from the barge.

The bail now rises with the shovel to the dump-` ing position of Figure 5, the counterweights doing a large portion of the work and power being. required only for lifting the actual load and what little extra weight is required to insure return of the shovel by gravity.

When the dumping position has been reached the material gravitates from the shovel through the channel 3| toward the screen. To aid in emptying the shovel, I provide a senil-cylindrical tank 48l above the shovel which is pivotally suspended from a shaft 82 and is slightly overbalanced to normally return to a position of rest, the heavier side being supported by a plunger 83 slidable in a cylinder 84. As the shovel rises to dumping position, the edge of the shovel strikes the plunger and tilts the heavier end of the tank upward, whereby a load of water contained in the tank is emptied into the shovel and made to aid in ilushing the shovel and the shovel channel. It will be understood, of course, that there is considerable water in the shovel as it rises and that the tank will be relled each time between operations. r

After dumping the shovel is allowed to descend and the bail descends with it. In passing through the position of Figure 1, the bail is first secured to the barge by hooks 1I whereupon the shovel is released from the bail by operation of pawl 11.

Next the shovel is pulled upward, in a rearward direction by cable 56 to assume the position of Figure 2 and is then allowed to drop downward into engagement with the river bottom as shown in Figure 3. From this position it is pulled forwardvby cable 55 to scoop up a load and to return to the position shown in Figure 1.

It will be noted (Figures 3 and 4) that the shovel is provided, at its upper rear edges, with rollers 85. These rollers impinge upon the sides of the bail as the shovel approaches the latter and serve to bring the shovel back to a desired angularit-y for dumping, when it has been allowed relative freedom of play during the scooping action by adjustment of the straps 5l as shown in Figure 4.

The material is discharged from the shovel in its raised position upon the shovel channel which latter discharges upon the sluice channel 21. This channel feeds the material into the rotary screen 24 which drops the finer material upon a suitable separating means such as a riilie board and discharges the coarser material upon the conveyor 26 for stacking. It is apparent that when material is encountered, such as clay, which carries no precious metal, it may be discharged directly from the sluice channel upon the conveyor'without being screened by interposing a trough 86 between the sluice channel and the conveyor.

My dredger construction lends itself very well to the arrangement of a plurality of units in multiple formation. It is often desirable to ar.- range a plurality of units in side by side relation with shovels operating at different depths so as to progressively attack different strata. Some of these strata may be non-metal bearing and may be discharged directly upon the conveyor while other strata may call for screening and separau tion.

While the dredger moves stepwise across the stream successive units will thus successively attack different strata, and the material of each stratum may be: thus treated'individuallyv without interference of material of different:V character;

Diierentunits. may. thus. be arranged in: side by" side relation. by coupling: a: plurality of L units such as. shown. inA Figure 9 bysuitable anchoring means such indicated. at 81. Theishovelchannels of these unit'sishouldlbeof. different. lengths so as to cause the shovelstoioperate. atdiierent depths..

Or different. shovels may be.` arranged in side by side relation on a single. barge as indicated in .Figures 12 and;1-3 In thisiform single barge 38* is 'shcwnl as*y havingy threel'wsell's 89; acconnnof dating. as many shovel.' units-l 99.. Figurev l2'shows how. these. units are` arrangedif'or operating; at diferentdepths, so that each. successive shovel operates on. a deeper layer'oflmaterialfand takes up dredging where. theJ preceding. onef lays. 01T.

Figure. 14 shows a caisson'. 91.' which.1 may' be suitably placed on'.V one sideof the: barge. as: at 92 in Figure 9 for lowering.: intotheriver bed by means ofi a cable S3. This; caissonfis. made in the.' formof a. Vertical.cylinden'having a sharp bott'orn edge asA ati 94 adapted; t'o curia iznt the river bottoinand having-fa rubberiiang'efgmalring a hermetic seal with the river bottom.. Water may be pumpedout of: this caisson..tlirough. a pipe 99' extendingtothe bottom thereofffwhereupon. the river bottom .enclosed by thecaisson is free for. inspectionv and sampling.

As an additional.' advantage: of` my counterweight bail, it might be pointed out that atv times the shovel may.V be' called upon. to. digl into an embankment' omits ascentandinrth'atcase the bail. will urge the shovel.v into? the embankment e and will hold.` the shovelagainst. backingv away from. the embankment., Atithesam'e time the counterweights willlact tciadd: pov/erf to thev for- Ward digging operation..

I claim.:

1. Inadredger, a'b'arge; ashovel', means'ior mounting. the: same., with: freedom of. scooping action below theb'arge. and of: ascending. motion toward dumping'. position.. ai counterweight; and connectingy means. between. the latter and the shovel,y the latter. means including.` means for rendering the counterweight active to'. aid in lifting the shovel during the ascent, an'd..for retaining the cou-nterweight. ina an inactive. posiu tion. during the sccopingcperation'.

2. In. adredger, a bargehavinga front. gantry rising. therefrom,- a: shovel; means'for swingably mounting the same' with. freedom' of. scooping action below. the barge andof ascending motion at the. rontofthelb'argetodumping position, a cable fori actuating the shoveland beingguided over the front'gantry; Vandlamovable' guide for the cable, the latter guidebeingmovableon an arc corresponding'. substantiallyto that described by the ascending shovel, a: cab'lehaving oneend connected'to the guide and having.` a counterweight at its other end, and means for' training the cable to exert-upward pulli on the. guide, the counterweight being' sufficiently' heavy to overbalance. the weightof theguideiwhen thelatter is insubstantially horizontal position..

3. In a dredger, a shovel, a'. shovel channel supporting the: same, means. for moving the shovel to scoopupj-a.loadaridltoascendto dumping. position for discharging the load on.Y the Vshovel channel,- a Waterta'nk mounted at the point ofV discharge, and means actuated by. the

ascending shovel for discharging water fromthe tank upon the shovel for flushing' the latter;

4..In. a dredger,` a shovel,V av shovely channel supporting the same, means for moving. the. shovel to scoop-'upfaloadi and to? ascend to.' dumping position for discharging the load on the shovelfchannel, a: water' tanki tiltably. mounted ati the. point".v of' Idischarge and means actuated by the ascending shovel for tilting the tank Whereby'theilatten is madefto discharge the water into. the shovelfor' flushing the load4 into the shovel channel..

5:. Inadredgenvatiltable guide, a shovel channelLslid'a-ble thereon, a shovelV connected to the channel, means for operating the shovel' for dredgingoperations anda bail coactingwith the shovel, they bail. being swingably mounted in coaxial Vrelation to the.' guide.

6..A dredger comprising a'. barge having a plurality of. recesses extending' from theV front edge into the body thereof,d a shovel for. each recessv and. swingable shovel-operating. means movablein the recesses. in. parallel planes. for sco'tping` action of:A the. shovels underneathfthe barge in parallel lanes, the. recesses being.` of diierent. lengthsr and. the. shovel-operating.' means being correspondingly constructed for operation atfdifferentldepths, whereby the shovels are. made to operate on. lanes of progressively increasing depth andy whereby the. stratum operated on" by each'. shovel isl kept'. separate from the strata operated oni by' theA other shovels for separate treatment if' desired..

7. In adredgerg a-tilt`able guide, ashcvelchannel slidable. thereingthe guide. and` the. channel having spaced confronting bottom. faces and spaced. ccnt'rontinglateral flanges anti-friction bearing; members supported; by each end ofi the guide. in said` spaces between the bottom. faces andi betweenthe. flanges, andianti-frictionbearing! members supported. o'n the extreme. end of the. shovel.' channel, th'e latter bearing` members being: positioned. to. clearl the bearing.v members on the: corresponding" endA of. the guide'.` when the said endof thechannel. enters into the guide.

8. In. adredger, aitilt'able guide, a shovel channel slidable. therein,. the. guide and. the channel having spaced confronting.' bottom' faces. and spaced confronting' lateral flanges, anti-friction bearing members supported' by eachend of the guide in'. said spaces' between the bottornfaces and between the ranges,- and. anti-frictionbearing members supported! onthe extreme end'of-"the shovel channeLthe latterbearing members being positioned toV clear the. bearing members on the corresponding endl. of.- the4 guide when the said end of the channel.V enters into the guide, the extreme; end of the channeland the opposite end of. the` guide? having registering stops for limiting the movement of the channel in the guide.

9. In. ai dredger; a. shovel! channel, ashovel, means for'pivotallyisecuring the bottom oyf the shovel. to the' bottom of the shovel channel, a strap, means forpivotally. securing the same to the channel at a higher point, and means for securing thestrap to theshov'el .either Xedly or witha limited arfio'un't'of. play.

10; In. a dredger;` a shovl channel, an shovel, means for pivotallysecuring.v the bottom of the shovel. to. the bottom of'tlle shovel channel, a strap.,v means'for'pivotally securing the same to .theA channel.` at a ponitznignerftnan. the bot-tcm thereof," and'. means for. securing@ the strap to the shovel With a limited-famountloi play.

1l?. In adredger," ashovellcha'nnel., means for mounting the same.. with freedom ofswinging movement, a. shovel, A means: for" pivotallysecu@ ing the same to the bottom of the shovel channel, a strap, means for pivotally securing the same to the channel at a point higher than the bottom, means for securing the strap to the shovel with a limited amount of play between normal and retracted positions, and means outside the shovel and the shovel channel for returning the shovel from a retracted to a normal position during a swinging movement of the channel.

12. In a dredger, a barge, a shovel, means for swingably mounting the shovel with freedom of scooping action and of ascending motion toward dumping position, a bail, means for swingably mounting the saine to describe an arc corresponding substantially to that described by the ascending shovel, a cable for actuating the shovel being guided to pass over the bail, and means for locking the bail to the barge prior to the scooping operation.

13. In a dredger, a barge, a shovel, means for swingably mounting the shovel with freedom of scooping action and of ascending motion toward dumping position, a bail, means for swingably mounting the same to describe an arc corresponding substantially to that described by the ascending shovel, a cable for actuating the shovel being guided to pass over the bail, means for locking the bail to the barge prior to the scooping operation, and means for hooking the shovel to the bail after the scooping operation and for simultaneously freeing the bail for ascent with the shovel.

14. In a dredger, a barge, a shovel, means for swingably mounting the shovel with freedom of scooping action and of ascending motion toward dumping position, a bail, means for swingably mounting the same to describe an are corresponding substantially to that described by the ascending shovel, a cable for actuating the shovel being guided to pass over the bail, and means for hooking the shovel to the bail, whereby a lifting effect brought to bear on the bail is transmitted to the shovel.

15. In a dredger, a tiltable guide, a shovel channel confined therein with freedom of sliding movement between positions of full engagement and positions of partial engagement, anti-friction bearing means carried by the guide and supporting the channel in spaced and parallel relation to the entire wall of the guide when the guide and the shovel channel are in full engagement, and additional anti-friction bearing means carried by the end of the channel for sustaining the latter in the same relationship during partial engagement.

16. In a dredger, a barge, a bail, means for swingably supporting the latter on the barge, means for detachably securing the free end of the bail to the barge, a gantry rising from the barge in the proximity of the securing means. a second gantry rising from the barge in spaced relation to the former, a counterweight and a flexible connection between the bail and the counterweight, the said connection being guided over the gantries for causing the counterweight to exert a lifting effect on the bail.

1'7. In a dredger, a barge, a bail, means for swingably supporting the latter over an intermediate section of the barge, means for detachably securing the free end of the bail to the front edge of the barge, a gantry rising from said front edge, a second gantry rising from the rear edge of the barge, a counterweight, and a flexible connection between the bail and the counterweight, the said connection being guided over the gantries for causing the counterweight to have a lifting effect on the bail.

18. In a. dredger, a barge, a bail, means for swingably supporting the latter on the former, means for detachably securing the free end of the bail to the barge, a shovel, and means for guiding the latter past the securing means, the shovel having means for attaching itself to the bail and for freeing the bail from the barge.

19. In a dredger, a shovel channel, a shovel having hinged connection with the shovel channel, a strap pivoted to the shovel channel and having a -pin hole and a slot therein and a pin for securing the strap to the shovel, the pin being engageable with the shovel through the pin hole or the slot in the strap for securing the shovel to the channel in a position of fixed relationship or with limited freedom of angular play.

20. In a dredger, a barge, a bail, means for swingably supporting the latter on the barge, a counterweight, a connection between the counterweight and the bail arranged and adapted to pull the bail upwardly from a downwardly inclined position, and means on the barge automatically engaging the bail for holding the same against the weight of the counterweight when the bail is moved to a downwardly inclined position.

21. A dredge comprising a barge having a superstructure, a dipper mounted on said superstructure to swing from a lower position into an upper discharging position, means for ejecting water into said dipper in said upper position, and means actuated by said dipper for controlling the operation of said ejecting means.

ARTHUR C. CRAWFORD. 

